Method for fabricating electrical contact buttons

ABSTRACT

An interposer having one or more hollow electrical contact buttons disposed in a carrier. The interposer is formed by disposing sacrificial posts in vias of the carrier. The electrical contact buttons are formed on the sacrificial posts by a metallizing process in desired pattern using a mask. The sacrificial posts are made of a material that thermally decomposes upon application of heat without altering the carrier or the electrical contact buttons.

This application is a division of U.S. patent application Ser. No.10/715,288, filed on Nov. 17, 2003 now U.S. Pat. No. 7,137,827 forInterposer With Electrical Contact Button And Method.

FIELD OF THE INVENTION

This invention relates to an interposer with electrical contact buttonsand a method for making the electrical contact buttons and theinterposer.

BACKGROUND OF THE INVENTION

Land Grid Array (LGA) interposers provide an array of interconnectionsbetween a printed wiring board (PWB) and a chip module, such as aMulti-Chip Module (MCM). LGA interposers allow connections to be made ina way that are reversible and that do not require soldering as, forexample, in ball grid arrays and column grid arrays. Ball grid arraysare unreliable on large areas because the lateral thermal coefficient ofexpansion driven stresses that develop exceed the ball grid arraystrength. Column grid arrays hold together despite the stresses but aresoldered solutions and, thus, do not allow field replacibility of thechip modules. Field replacability is important because it saves thecustomer significant cost in maintenance and upgrade of high-endcomputers for which LGAs are typically used.

Currently, there are at least two LGA types commercially available. Eachsuffers from serious problems. One type utilizes as the conductingmedium a composite of siloxane elastomer and silver particles, whichwhen mixed above the percolation threshold concentration, conductselectricity. The composite is injection molded into the shape of buttonsacross a full LGA in one injection mold operation, and is, thus, a goodsolution from the standpoint of manufacturing the LGA cost-effectively.Another advantage is that it can operate at low contact forces on theorder of 30 to 80 grams per contact. Typically, current LGA's haveseveral thousand contacts per interposer. A disadvantage is that thecomposite of elastomer and silver particles is itself a poor elastomer.In other words it undergoes significant plastic deformation undertypical operating conditions and leads to eventual failure.

Another type of LGA interposer consists of an area array of buttoncontacts each made of a random spaghetti coil spring. These springs areformed one at a time by injecting at high speed a length of gold-coatedmolybdenum wire into a mold. This interposer works reliably. However,they have a disadvantage of being expensive because of thebutton-by-button fabrication method. Also, they require being squeezedwith a very high contact force between the MCM and the PWB. Forces onthe order of 100 to 120 grams per button are typically required. Suchhigh forces, once multiplied by the large number of buttons on aninterposer, can cause deformation of the MCM and the PWB, and have beenknown to crack the chips mounted on the MCM. Further, these interposersdo not scale reliably to larger MCMs with higher input/output (I/O)requirements. In addition, these interposers are also inconsistent withthe introduction of organic packaging. Organic packages strive toreplace expensive ceramic MCMs and offer better electric performance.Organic packages are much softer and more fragile and could thus onlytolerate LGA forces much smaller than 100 to 200 grams per button.

SUMMARY OF THE INVENTION

An interposer embodiment of the present invention comprises a hollowbody of electrically conductive material disposed in an electricallyinsulating carrier.

In a second interposer embodiment of the present invention in which theinterposer connects a module to a printing wiring board, the interposercomprises a carrier that has at least one electrically conductive viaand that is disposed so that the via is in registration with a connectorof the module and a connector of the printed wiring board. At least onehollow electrical contact button is disposed in the via for electricalcontact with the connector of the module and the connector of theprinted wiring board.

In one variation of the above noted interposer embodiments, the hollowbody comprises no voids. In a second variation, the hollow bodycomprises one or more voids. In a third variation, the hollow bodycomprises at least two voids in registration with one another anddisposed on opposite sides of the carrier.

A method embodiment of the present invention fabricates an electricalcontact button by forming a sacrificial post, forming a pattern ofelectrically conductive material on the sacrificial post and removingthe sacrificial post, thereby providing the electrical contact button.

Preferably, the electrically conductive material is selected from thegroup consisting of: copper, nickel, gold, chromium, titanium, lead,tin, bismuth, antimony, tungsten, molybdenum and alloys thereof.

In alternate embodiments of the method, the pattern of electricallyconductive material is formed on the sacrificial post by a processselected from the group that consists of: physical masking andphotoresist. The physical masking process may be selected from the groupof vacuum deposition and electroless plating.

The photoresist process may be selected from the group of metal additiveand metal subtractive. The photoresist process may place metal on thesacrificial post by vacuum deposition, sputtering, electroless plating,laminating foil or preformed sheet metal.

Preferably, the sacrificial post is formed of a material that thermallydecomposes and vaporizes. The sacrificial post material may be selectedfrom the group of polymethylmethacrylate, polyalpha-methylstyrene,polyethyleneoxide, polyphenylene oxide or polystyrene and othermaterials that are known to burn off, vaporize depolymerize, or otherwise vacate the original position.

Preferably the sacrificial post is removed by thermal decomposition.

The electrically conductive pattern is continuous in some embodimentsand discontinuous in other embodiments. For example, the discontinuouspattern comprises one or more voids.

In a second embodiment of the method of the present invention, thesacrificial post is formed in a carrier. Preferably, the carrier isformed of an electrically insulating material, which may be selectedfrom the group consisting of: polyimide, polyester, ceramic, quartz,glass, polymer coated metal, polytetrafluoroethylene and oxides.

In a third embodiment of the method of the present invention, thecarrier includes a plurality of perforations in which a plurality of thesacrificial posts are formed, wherein a pattern of the electricallyconductive material is formed on each of the sacrificial posts, andwherein the sacrificial posts are removed to thereby form a plurality ofelectrical contact buttons.

Preferably, a coating of electrically conductive material is formed onat least one of the perforations before the sacrificial posts are formedto complete the electrical connection between the top of the contact andthe bottom.

Preferably, the sacrificial posts are formed in the perforations byinjection molding.

Preferably, the carrier is formed of an electrically insulatingmaterial, which may be selected from the group that consists of:polyimide, polyester, ceramic, quartz, glass, polymer coated metal,polytetrafluoroethylene and oxides.

Preferably, the electrically conductive material is selected from thegroup consisting of: copper, nickel, gold, chromium, titanium, lead,tin, bismuth, antimony, tungsten, molybdenum and alloys thereof.

In variations of the third embodiment, the pattern of electricallyconductive material is formed on the sacrificial posts by a processselected from the group that consists of: physical masking andphotoresist. The photoresist process may be either metal additive ormetal subtractive. Either the physical masking process or thephotoresist process may use either vacuum deposition or electrolessplating.

Preferably, the sacrificial posts are removed by thermal decompositionand are formed of a material that thermally decomposes and vaporizes.The sacrificial post material may be selected from the group consistingof: polymethylmethacrylate, polyalpha-methylstyrene, polyethyleneoxide,polyphenylene oxide or polystyrene and other materials that are known toburn off, vaporize depolymerize, or other wise vacate the originalposition.

The electrically conductive pattern is continuous in some embodimentsand discontinuous in other embodiments. That is the discontinuouspattern comprises one or more voids.

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further objects, advantages and features of the presentinvention will be understood by reference to the following specificationin conjunction with the accompanying drawings, in which like referencecharacters denote like elements of structure and:

FIG. 1 is an assembly in which the LGA interposer of the presentinvention may be used;

FIG. 2 is a diagram for a physical mask process flow for metallizingthrough holes in an interposer carrier of the method of the presentinvention;

FIG. 3 is a diagram for an alternate photoresist process flow formetallizing through holes in an interposer carrier of the method of thepresent invention;

FIG. 4 is a diagram for a process flow of molding a sacrificial postinto a premetallized LGA carrier and six alternate methods forcompleting fabrication of the LGA interposer array of the method of thepresent invention;

FIG. 5 is a perspective view of an empty carrier before metallization ofthrough holes that is common to all six methods of FIG. 4;

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 5;

FIG. 7 is a perspective view of an empty carrier before metallization ofthrough holes that is common to the first six methods of FIG. 4;

FIG. 8 is a perspective view of a carrier with metallized through holesthat is common to the first six methods of FIG. 4;

FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 8;

FIG. 10 is a perspective view of a carrier with a template ofsacrificial posts in metallized through holes that is common to the sixmethods of FIG. 4;

FIG. 11 is a cross-sectional view taken along line 11-11 of FIG. 10;

FIG. 12 is a perspective view of a carrier with a template ofsacrificial posts that is common to all six methods;

FIG. 13 is a process flow of method 1 of FIG. 4;

FIG. 14 is a cross-sectional view of a physical mask for yielding a fullmetallized shell button;

FIG. 15 is a cross-sectional view of a physical mask for yielding apartially metallized shell button;

FIG. 16 is a diagram of the process flow of the methods 1 and 6 of FIG.4;

FIG. 17 is a perspective view of an interposer carrier before thesacrificial posts are removed;

FIG. 18 is a cross-sectional view taken along line 18-18 of FIG. 17;

FIG. 19 is the cross-sectional view FIG. 18 with the sacrificial postsremoved;

FIG. 20 is a perspective view of a carrier with unmetallized sacrificialposts docked into a physical mask;

FIG. 21 is a diagram of the process flow of the method 2 of FIG. 4;

FIG. 22 is a diagram of the process flow of the method 3 of FIG. 4;

FIG. 23 is a diagram of the process flow of the method 4 of FIG. 4;

FIG. 24 is a diagram of the process flow of the method 5 of FIG. 4;

FIG. 25 shows exemplary patterns of metallized sacrificial posts beforethe post removal step;

FIG. 26 shows the exemplary patterns of FIG. 25 after the post removalstep; and

FIG. 27 is a perspective view of the LGA interposer with an exemplarymetallized button pattern of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an assembly 100 includes an LGA interposer 102disposed between a PWB 104 and an MCM module 106, a heat sink 108, aspring 110 and posts 112. PWB 104, MCM module 106 and heat sink 108 areheld together under force supplied by spring 110, transferred throughposts 112, posts 112 being attached to heat sink 108. Posts 112 arepreferably metallic.

MCM module 106 includes one or more electrical contacts 114 and PWB 104includes one or more electrical contacts 116 disposed in aligned andspaced relationship to contacts 114. LGA interposer 102, which is shownin an exploded view at detail 118, includes one or more electricalcontact buttons 120 disposed in aligned relationship to contacts 114 and116.

When spring 110 is adjusted by means of adjuster 122, PWB 104, LGAinterposer 102 and MCM module 106 are pressed toward one another so thatcontacts 114 of MCM module 106 and contacts 116 of PWB 104 make a forcedphysical and electrical contact with respective ones of contacts 120 ofLGA interposer 102.

LGA interposer 102 includes a carrier 124 having one or more throughholes or vias in which contact buttons 120 are disposed. Carrier 124 isdisposed between physical downstops 126, which are affixed to an LGAframe 128. LGA frame 128 provides a stop limit to the amount ofcompression that spring 110 can exert in bringing contacts 114, contacts116 and contact buttons 120 into physical and electrical contact.

It will be apparent to those skilled in the art that although twocontacts 114, two contacts 116 and two contact buttons 120 are shown,more or less of each may be provided. It will also be apparent to thoseskilled in the art that assembly 100 can include LGA interposer 102disposed between any two devices having contacts that need connections,MCM module 106 and PWB being shown by way of example.

Preferably, contact buttons 120 are made according to the methods of thepresent invention and can have any of a variety of metallizationpatterns, for example any of those shown in FIG. 26.

According to the method of the present invention, LGA interposer 102 ismade by starting with a perforated carrier 140 or 142, as shown in FIGS.5 and 7. Carrier 140 is fabricated by perforating a Kapton plastic sheetwith holes (vias) in the desired positions of contacts.

Carrier 140 is preferably an electrically insulating material that maybe either a flexible sheet or a more rigid plate. The electricallyinsulating material, for example, may be polyimide, polyester, ceramic,quartz, glass, polymer coated metal, polytetrafluoroethylene, oxides orthe like. Another type of carrier that could be used is a low expansionmetal or metal alloy which has an insulator layer over it's entiresurface and through the vias. An example of the latter could bemolybdenum with low expansion coefficient with a thin coating of lowexpansion polymer such as pyrromellitic dianhydrideheneylene diamine(PMDA-PDA) polyimide. Then the interposer construction would proceed asdescribed herein.

Metal pads must be fabricated on each side of the holes and connected ina manner that is electrically continuous through the hole. Two mainapproaches to this are a direct metallization using physical masks toshield areas where metal is not desired and a subtractive method fordefining this metallurgy. In the subtractive method, metal is firstdeposited on both sides and through the vias of the planar substrate (byany means, including plating, plasma spray, etc), followed byapplication of photoresist, expose, develop and etch removal of unwantedmetal.

Referring to FIG. 2, in the direct metallization approach, at steps 2Aand 2B a physical mask 144 is oriented so that one or more openings 146therein are aligned over one or more perforation holes 148 in carrier140 and brought into contact with one another. Openings 146 may have anysuitable shape, for example, circular, star, cross and other shapes. Atstep 2C, metal is deposited onto carrier 140 by such a method that ametal coating 154 will result on the open areas on top of carrier 140and down onto the side walls of the hole or via 148. At step 2D,physical mask 144 is removed. Carrier 140 is then flipped over and theother side is metallized in similar fashion (e.g., steps 2A, 2B and 2Care repeated), thereby creating a continuous metal path from the top ofcarrier 140, down the sides of hole 148 and onto the other side of thecarrier 140 as shown at step 2E and in FIGS. 8 and 9.

Referring to FIG. 3, the subtractive method for patterning the metal oncarrier 140 is shown. The method begins at steps 3A and 3B by depositinga coating 162 of metal on both sides, as well as hole 148, of carrier140. At step 3C. a coating 165 of photoresist is deposited over metalliccoating 162. At step 3D, a mask 168 having circular patterns of a largerdiameter than holes 148 is placed over each side of carrier 140 so thatthe circular patterns are concentrically aligned with and cover holes148. One side of carrier 140 is then exposed to ultraviolet light. Mask168 is then removed from this side. Carrier 140 is flipped. The secondside is then exposed to ultraviolet light, the metal etched from theexposed areas and mask 168 is then removed from the second side. Metalis etched away from the exposed areas on both sides. At step 3E,photoresist coating 165 is developed on both sides simultaneously,thereby removing photoresist coating 165 to result in plated throughhole 148P shown at step 3F.

It will be apparent to those skilled in the art that methods other thanthose shown in FIGS. 2 and 3, known currently or in the future, can beused to metallize holes 148.

Referring to FIG. 4, step 4A corresponds to step 3F. At step 4Bsacrificial posts 180 are inserted into holes 148. Sacrificial posts 180are formed in the shape of the final contacts, but will ultimately beremoved after being used as a template for final metallization. Carrier140 with sacrificial posts 180 installed is shown in FIGS. 10-12.

Sacrificial posts 180 can be formed in carrier 140 by any suitablemethod, for example by injection molding the full two-dimensional (2D)array at once. In other methods, sacrificial posts 180 may beprefabricated and then inserted into the holes instead. Nevertheless,sacrificial posts 180 will usually be made of a material that thermallydecomposes and vaporizes.

For example, sacrificial posts 180 may be formed with a polymer, such aspolymethylmethacrylate, polyalpha-methylstyrene, polyethyleneoxide,polyphenylene oxide or polystyrene. Indeed, most polymers under theright temperature conditions will thus decompose.

If carrier 140 is made of a thin ceramic material, instead of plasticused in the example, then higher temperature conditions for postdecomposition could be employed and a great variety of materials used asthe sacrificial post. Other options for the sacrificial posts are theuse of solution dissolvable materials.

The next step is metallization over the sacrificial polymer contactbutton. This can be carried out in many ways. Six different methods areoutlined in FIG. 4 and designated as methods 1 through 6, which will bedescribed in detail hereinafter.

Once sacrificial posts 180 have been metallized, the next step is toheat the assembly to a temperature and under conditions such thatsacrificial polymer posts 180 will depolymerize and vaporize orotherwise decompose and vaporize. This leaves a hollow metal cagestructure that sometimes resembles a birdcage, examples of which areshown in FIG. 25.

Referring to FIGS. 4 and 13, method 1 for metallizing sacrificial posts180 begins at step 13A by depositing (as by sputtering, vacuumdeposition or other suitable deposition technique) a metallic coat orfilm 188 on physical mask 190 that is disposed on carrier 140. Metalliccoat 188 also covers any sacrificial posts 180 installed in carrier 140plate. At step 13B, physical mask 190 is removed as by lifting, therebyleaving metallic coat 188 disposed on sacrificial posts 180 and incontact with plated through holes 148P. At step 13C, sacrificial posts180 are decomposed, thereby leaving birdcage shaped contacts 196. Method6 is identical to method 1, except that the metal coat is deposited byspraying with electroless plating seed compound and then electroplatingthe metal.

Referring to FIGS. 25 and 26, birdcage contacts 196 may have a varietyof metallization patterns. The metallization patterns are shown beforedecomposition of sacrificial posts 26A through 26H in FIG. 25 (i.e., inunfinished form where the metal is still fixed on the sacrificial posts)and after decomposition in FIG. 26. These patterns are formed bydifferently shaped masks. For example, FIG. 14 shows a cross section oftwo contact positions of a physical mask 190 that are shaped to yieldthe metallization pattern shown at 25G of FIG. 25 and 26G of FIG. 26.FIG. 15 shows a cross section of two contact positions of a physicalmask 190 that are shaped to yield the metallization pattern shown at 25Aof FIG. 25 and 26A of FIG. 26. The physical masks illustrated in FIGS.14 and 15 can be used for either method 1 or method 6. Other mask types,such as purely 2D masks like molybdenum masks can alternatively be used.

Referring to FIG. 16, method 1 is further shown as bringing physicalmask 190 and carrier 140 with installed sacrificial posts into contactwith one another. Physical mask 190 has mask patterns that correspond topattern 25H of FIG. 25 and 26H of FIG. 26. These patterns contain a holeto permit passage of light from a light source. FIGS. 17 and 18 alsoshow the metallization pattern of 25H of FIG. 25 before decomposition ofsacrificial posts 180. FIG. 19 shows the metallization pattern of 26H ofFIG. 26 after decomposition of sacrificial posts 180. FIG. 20 shows aphysical mask 190 that bears a mask pattern corresponding to themetallic pattern 26E of FIG. 26.

Referring to FIGS. 4 and 21, method 2 for metallizing carrier 140 withinstalled sacrificial posts 180 begins at steps 21A and 21B by blanketmetallizing both sides of carrier 140 as by vacuum deposition (e.g.,sputtering or evaporation). Then both sides are coated with photoresist.The photoresist is exposed to ultraviolet light through a photomaskhaving the desired pattern of metallization at step 21C. The exposedphotoresist area is developed and the masked areas are wet etched toremove metal at step 21D, thereby leaving the desired metallizationpattern. The sacrificial posts 180 are then decomposed at step 21E,thereby leaving the desired birdcage contact 196.

Referring to FIG. 22, method 3 is identical to method 2, except that themetal is deposited to both sides of carrier 140 by electrolessdeposition.

It should be apparent to those skilled in the art that other methods ofdepositing can be used, such as laminating foil or preformed sheet metalin a shape like an egg carton could be laminated and positioned inregistry with the vias. In this embodiment, sacrificial posts may or maynot be used.

Referring to FIG. 23, method 4 uses a metal additive approach. Method 4begins at step 23A by coating both sides of carrier 140 withphotoresist. At step 23B, the photoresist is exposed to ultravioletlight through a photomask having a negative pattern to that of thephotomask used in methods 2 and 3. The exposed areas of the photoresistare developed at step 23C. At step 23D, a metallic coat is vacuumdeposited on both sides of carrier 140. At step 13E, the photoresist islifted off carrier 140 and sacrificial posts 180 are decomposed, therebyleaving the birdcage contact 196.

Referring to FIG. 24, method 5 is identical to method 4, except that themetal coat is deposited to both sides of carrier 140 by electrolessdeposition.

Many different birdcage patterns are envisioned. Those shown are onlyfor illustration. The patterns can range from being fully metallized, tobeing only a fine lacy structure. Furthermore, the same interposer couldhave some posts with some patterns and other posts with differentpatterns to serve specialized functions.

One type of special function pattern includes a window through which anoptical signal could pass as shown at 26H in FIG. 26. Thus, if the chipor chip module that the interposer were making contact with had acombination of electrical signals and optical signals, these could bothbe accommodated by the same birdcage contact type.

Methods other than methods 1 through 6 can be used to metallize thesacrificial posts. For example, an entire 2-D array of the metal piecescould be prefabricated and attached to the metallized planar substrate.

In still other embodiments, post shapes of different types can be used.Short and wide (relative to the post-to-post pitch, or tall and narrowwould be two typical types. Other more specialized shapes might also bedesirable. For instance if a great deal of vertical compressibility weredesired in the final metal contact, one could fabricate the sacrificialposts to have a 3-D shape with accordion like serrations. Theseserrations, once metallized, and the posts burned away, would provideaccordion like compressibility while minimizing metal fatigue.

In another embodiment, the button could be fabricated as a cylinderhaving slots parallel to the cylinder axis so as to make bending moredifficult without significantly reducing compressibility along thecylindrical axis.

Different metals can be used to achieve the optimum performance of thebutton. Common metals used in microelectronic fabrication, such ascopper, nickel, gold, chromium, titanium, lead, tin, bismuth or antimonyare applicable as well as other less common materials that may be usedfor greater metal fatigue toughness, such as nickel/iron alloys,beryllium copper, nickel/titanium alloys or metals for low thermalexpansion, such as tungsten or molybdenum.

The present invention having been thus described with particularreference to the preferred forms thereof, it will be obvious thatvarious changes and modifications may be made therein without departingfrom the spirit and scope of the present invention as defined in theappended claims.

1. A method for fabricating an electrical contact button comprising: forming a sacrificial post in a perforation of a carrier by injection molding a material in said perforation, wherein said material thermally decomposes and vaporizes; extending said sacrificial post with a top portion beyond a top surface of said carrier and a bottom portion beyond a bottom surface of said carrier; forming a pattern of electrically conductive material on both said top portion and bottom portion of said sacrificial post; and removing said sacrificial post, thereby providing said electrical contact button.
 2. The method of claim 1, wherein said electrically conductive material is selected from the group consisting of: copper, nickel, gold, chromium, titanium, lead, tin, bismuth, antimony, tungsten, molybdenum and alloys thereof.
 3. The method of claim 1, wherein said pattern of electrically conductive material is formed on said sacrificial post by a process selected from the group that consists of: physical masking and photoresist.
 4. The method of claim 3, wherein said physical masking process is selected from the group that consists of: vacuum deposition and electroless plating.
 5. The method of claim 3, wherein said photoresist process is selected from the group consisting of: metal additive and metal subtractive.
 6. The method of claim 3, wherein said photoresist process is selected from the group that consists of: vacuum deposition, sputtering, electroless plating, laminating foil and preformed sheet metal.
 7. The method of claim 1, wherein said sacrificial post material is a polymer.
 8. The method of claim 1, wherein said sacrificial post material is selected from the group consisting of: polymethylmethacrylate, polyalpha-methylstyrene, polyethyleneoxide, polyphenylene oxide and polystyrene.
 9. The method of claim 1, wherein said pattern is selected from the group consisting of: continuous and non-continuous.
 10. The method of claim 1, wherein said carrier is formed of an electrically insulating material.
 11. The method of claim 10, wherein said electrically insulating material is selected from the group consisting of: polyimide, polyester, ceramic, quartz, glass, polymer coated metal, polytetrafluoroethylene and oxides.
 12. The method of claim 10, wherein said carrier includes a plurality of said perforations in which a plurality of said sacrificial posts are formed by injection molding, wherein a pattern of said electrically conductive material is formed on each of said sacrificial posts, and wherein said sacrificial posts are removed to thereby form a plurality of electrical contact buttons.
 13. The method of claim 12, wherein a coating of electrically conductive material is formed on at least one of said perforations before said sacrificial posts are formed.
 14. The method of claim 12, wherein said electrically conductive material is selected from the group consisting of: copper, gold, nickel, titanium, and alloys thereof.
 15. The method of claim 12, wherein said pattern of electrically conductive material is formed on said sacrificial posts by a process selected from the group consisting of: physical masking and photoresist.
 16. The method of claim 15, wherein said physical masking process is selected from the group consisting of: vacuum deposition and electroless plating.
 17. The method of claim 15, wherein said photoresist process is selected from the group consisting of: metal additive and metal subtractive.
 18. The method of claim 15, wherein said photoresist process is selected from the group consisting of: vacuum deposition, sputtering electroless plating, laminating foil and preformed sheet metal.
 19. The method of claim 12, wherein said pattern is selected from the group consisting of: continuous and non-continuous.
 20. The method of claim 10, wherein said electrically insulating material is selected from the group that consists of: polyimide, polyester, ceramic, quartz, glass, polymer coated metal and polytetrafluoroethylene, oxides.
 21. The method of claim 1, further comprising: forming a metallic coating on a side wall of said perforation, thereby forming a metallic plated through perforation, and wherein said sacrificial post is formed in said metallic plated through perforation. 